Government Decides on Policy to Deal with Radioactive Sludge from Fukushima Daiichi NPS Accident

Information Update on Fukushima Nuclear Power Station, issued by JAIF on July 4th, 2011

The Japanese government has formulated its short-term policy to deal with radioactive materials stemming from the March 11 accident at the Fukushima Daiichi Nuclear Power Station (NPS), owned and operated by the Tokyo Electric Power Co., Inc. (TEPCO). Those materials have been detected in sludge throughout eastern Japan

from the process of water purification and sewage sludge, including dehydrated sludge from sewage-treatment plants, and materials from the process of its incineration, melting, and so forth. Relevant ministries were notified of the policies accordingly.

Based on the earlier short-term policy to secure safety in the treatment and disposal of disaster waste materials (including debris and sludge) from the accident, decided upon by the Nuclear Safety Commission (NSC) of Japan on June 3, the radiation doses for residents near disposal facilities and other installations, as well as for workers involved in such work, are to be held to less than 1mSv a year. Also, such levels are to be kept as low as possible in the areas of treatment, transportation, and storage.

Specifically, the following rules are to be abided by:

— First, when radioactive concentrations remain high with incineration, it is necessary to secure appropriate dust collectors.

— Second, if radioactive cesium concentrations are below 100,000Bq per kg, sludge and other materials may be stored temporarily at managed disposal sites, keeping appropriate distances from residential areas and the like.

— Third, if radioactive cesium concentrations are below 8,000Bq per kg, sludge and other materials may be disposed of in landfills on the condition that the sites are not later turned into residential areas and the like.

— Fourth, materials may be recycled as long as they are below clearance levels before being circulated on the market (i.e., assuming they are to be mixed with other raw materials). Also, when recycling is conducted as wet concrete or ground improvement agents, radioactivity concentrations of up to twice the clearance levels are permissible at the cement stage, given that they are to be diluted.

The Japan Atomic Energy Agency (JAEA) has evaluated the technical aspects of treatment and disposal of hydration sludge and other materials, setting parameters for incinerating, temporarily storing and using it as landfill, as well as the later use of disposal sites. All of those items were confirmed to be reasonable.